Formation of a Bilayer of ALD-SiO2 and Sputtered Al2O3/ZrO2 Films on Polyethylene Terephthalate Substrates as a Moisture Barrier

The moisture barrier properties of a co-sputtered Al2O3/ZrO2 single layer and a bilayer of ALD-SiO2 and co-sputtered Al2O3/ZrO2 were examined as potential candidates for OLED encapsulation. In the case of the single-layer, the water vapor transmission rate (WVTR) showed a strong correlation with the normalized film density. A dramatic decrease in WVTR was observed for the bilayer barrier film. The deposition sequence of the bilayer also influenced the WVTR, in that the ALD-first barrier showed lower WVTR than the Al2O3/ZrO2-first layer. This was attributed to the superior coverage of ALD-SiO2 film on particles and pinholes.